Three-phase motor cables are ordinarily manufactured and sold in many makers. In factories of the present Applicant as well, the motor cables are sold as, for example, robot cables (ORV Cable Series) (See Non-patent Publication 1). As a generally integrated catalog, a “general cable guidebook” issued by Hitachi Cable Ltd., for example, discloses various cable structures. Not only those disclosed therein, but also various other cable structures are publicly disclosed by many other makers.
In a broad sense, conventionally known three-phase motor drive cables, such as described above, are primarily classified into cables of three types, as shown in FIGS. 15(A), 15(B), and 15(C). FIG. 15(A) shows a conventional first type cable 1-1 (or, “cable structure 1-1” hereinafter). As shown therein, the first type cable 1-1 has a cable structure including three motor drive insulated wires 2, respectively, formed with an insulator 4 provided onto conductors 3. A sheath 8 is provided on the above-described, but no shield is provided thereon. FIG. 15(B) shows a conventional second type cable (or, “cable structure 1-2” hereinafter) 1-2. As shown therein, the second type cable 1-2 has a cable structure that includes three motor drive insulated wires 2 (U, V, and W), respectively, formed with the insulator 4 provided on conductors 3. In addition, a neutral wire (with the insulator 4 provided thereon) is arranged (the ground wire is a conductor on the side maintained to the ground potential, which ordinarily is alternatively called as a “ground wire,” and is a ground wire for the purpose of security). A sheath 8 is provided to surround the wires, but no shield is provided thereon. FIG. 15(C) shows a conventional third type cable 1-3. As shown therein, the third type cable 1-3 has a cable structure that includes three motor drive insulated wires 2, respectively, formed with the insulator 4 provided on conductors 3. In addition, the ground wire 6 (with the insulator 4 provided thereon) is arranged. A shield 7 is provided on the outer circumference of the above-described, and a sheath 8 is provided to surround the wires.
Further, although having not actually appeared on the market, cable structures described hereinafter are also known (see Non-patent Publications 3 and 4). FIG. 15(D) shows a conventional fourth type cable 1-4. As shown therein, the fourth type cable 1-4 has a cable structure including three motor drive dielectric core wires 2, respectively, formed with the insulator 4 provided onto conductors 3. A shield 7 is arranged to the above-described and a sheath 8 is provided thereon. As the last one, FIG. 15(E) shows a conventional fifth type cable 1-5. As shown therein, the fifth type cable 1-5 has a cable structure including three motor drive dielectric core wires 2, respectively, formed with the insulator 4 provided onto conductors 3. Further, three security ground wires 9 each provided with the insulator 4, a shield 7 is provided on the outer circumference thereof, and a sheath 8 is provided to surround the wires.
The present invention (and embodiments thereof) will be described using terms defined as follows. The term “conductor” refers a metal portion (generally, a portion of aluminum or copper) that allows electricity to travel or pass through, and that is an open conductor wire configured from a single wire or a strand wire (an aggregate of multiple wires). The term “insulated wire” refers to a wire that jacketed with an insulator, and that generally is provided without a sheath (outer protection jacket). The term “core” or “core wire” refers to an insulated wire formed by providing an insulator on a conductor (single wire or strand wire). The term “cable” refers to a wire formed in the manner that the core or core wire is single-stranded or multi-stranded, and a sheath is provided to surround the wires.
Non-patent Publication 1: http://www.okidensen.co.jp/prod/cable/robot/orv.html
Non-patent Publication 2: http://www.hitachi-cable.co.jp/catalog/H-001/pdf/07g—02_densan.pdf
Non-patent Publication 3: “Report Regarding High Tension Inverter-Used Cables”, Jan. 27, 2005, EMC-Countermeasure Technique WG for High Tension Inverter Cables, The Japan Electrical Manufacturers' Association
Non-patent Publication 4: “Evaluation of Motor Power Cables for PWM AC Drives” John. M. Bentley and Patrick J. Link, IEEE TRANSACTION ON INDUSTRY APPLICATIONS VOL. 33, NO. 2, MARCH/APRIL 1997